Many hundreds of thousands of people each year experience partial or complete blockage of the femoral artery attributable to plaque build-up in the artery. When this occurs, the supply of oxygen-rich arterial blood to the leg is reduced, causing pain and, if it is left untreated, eventually leads to amputation of the leg.
For some blockages, it is possible to remove the blocking tissue by angioplasty or atherectomy, thereby preserving the functionality of the femoral artery. For more complex blockages, however, it is sometimes necessary to altogether bypass the blocked femoral artery. In other words, it is sometimes necessary to attach a substitute conduit to the femoral artery at a location that is upstream (proximal) to the blockage and a location that is downstream (distal) to the blockage, with the substitute conduit assuming the function of the femoral artery in delivering arterial blood to the leg. Such a bypass procedure may be required when the femoral artery has become too occluded or otherwise impaired between the upstream and downstream locations to transport the flow of blood required of it.
Frequently, the bypass conduit of choice is the patient's saphenous vein. The saphenous vein is the principle vein in the leg, and it is the vein that normally returns oxygen-depleted venous blood upwardly through the leg to the trunk of the body, for eventual transport of the blood to the heart and lungs for replenishing the blood with oxygen. It happens, however, that other veins exist in the leg which can duplicate the function of the saphenous vein. Consequently, it is feasible to modify the saphenous vein for use as a substitute for a blocked femoral artery.
To bypass the femoral artery using the saphenous vein, the saphenous vein is surgically severed in the upper leg, near the groin, and in the lower leg, near the ankle, to establish a bypass segment. Then, the bypass segment is attached ("anastomosed") to the femoral artery to bypass the blockage in the artery.
Unfortunately, the saphenous vein cannot simply be used as an artery without modification. First, this is because the saphenous vein, like all major veins but unlike major arteries, includes many openings into which venous blood flow from smaller, so-called "side branches", i.e., tributaries and perforators, can enter the main venous blood path back to the heart. The skilled artisan will appreciate that to prevent the unwanted flow of arterial blood directly into the venous system via the saphenous vein, the side branches and perforators must be ligated. Stated differently, by ligating the side branches, arterial blood which is to be permitted to flow through the saphenous vein and thereby bypass the occluded segment of the artery is prevented from invading the venous system through the side branches.
Typically, side branches are ligated by constricting the side branches with sutures. Unfortunately, ligating side branches with sutures can be time-consuming and labor-intensive, because all the side branches must be located either by making a large number of small incisions in the leg or by making one very large incision. Also, it is difficult to ligate side branches with sutures in less-invasive procedures, i.e., endoscopically. Nevertheless, to render the saphenous vein suitable for arterial use, the side branches must be blocked, i.e., ligated.
A second problem which must be addressed when using the saphenous vein to bypass the femoral artery is that the saphenous vein, like all major veins but unlike major arteries, contains one-way valves which ordinarily would permit the flow of blood only toward the heart (i.e., venous blood flow), not away from the heart (as is required for arterial blood flow). Thus, to render the saphenous vein suitable for arterial use, the one-way valve problem must be addressed.
One way to address the one-way valve problem is to reverse the entire saphenous vein bypass segment in a procedure referred to as the "reverse" procedure. In the reverse procedure, the segment of the saphenous vein which is to be used to bypass the femoral artery is removed from the leg, physically turned 180 degrees, and then replaced in the leg and anastomosed to the femoral artery. Thereby, the flow of arterial blood through the vein holds the valves open, instead of forcing them closed. Also, the side branches can be ligated when the saphenous vein has been removed from the leg, prior to repositioning the vein in the leg.
It will be appreciated that the reverse procedure requires making a lengthy incision in the leg to permit removal and repositioning of the saphenous vein. This is traumatic to the patient, and contributes to the length of the patient's hospital stay and recovery time.
Not surprisingly, a second method has been developed to address the one-way valve problem without requiring completely removing and then repositioning the saphenous vein. In this second method, referred to as "in situ bypass", the saphenous vein is left in place, and a cutting device known as a valvulotome is pushed or pulled through the saphenous vein to cut or otherwise disrupt the one-way valves, rendering them incompetent and thereby permitting arterial blood flow through the saphenous vein.
In situ bypass is not without its complications, however. The requirement remains that the side branches to the vein must be ligated. In the context of in situ bypass surgery, this typically requires making a number of small incisions or a single, long incision along the length of the vein to provide a surgeon access to the side branches to enable the surgeon to ligate the side branches. In either case, the trauma problems noted above that are associated with making a large number of incisions, or a single lengthy incision, remain.
Moreover, in situ bypass surgery, like many surgical procedures, can require that the surgical site be frequently irrigated to improve visualizing the site. This is particularly true when the procedure is performed endoscopically, i.e., when an optical fiber is advanced into the saphenous vein along with the valvulotome to provide the surgeon with an image of the operating site on a video monitor in the operating room. It is possible, however, that over-irrigation can cause ancillary damage to the leg or compromise the vessel itself.
As recognized by the present invention and disclosed in the above-referenced patent applications, side branches to the saphenous vein can be ligated less-invasively using electro-cautery. As further recognized by the present invention, the same less-invasive electro-ligation principles which apply to saphenous vein side branches can also apply to varicose veins. More particularly, the present invention recognizes that varicose veins can be treated by electro-ligation of the veins using less-invasive principles.
It is therefore an object of the present invention to provide a device for in situ saphenous vein bypass surgery that can less-invasively ligate side branches of a saphenous vein without requiring that excessive incisions be made in the patient's leg. Another object of the present invention is to provide an apparatus and method for less invasively bypassing a blocked femoral or distal artery. Still another object of the present invention is to provide an apparatus and method for in situ saphenous vein bypass surgery which is easy to use and cost-effective to manufacture.